Post passivation interconnection schemes on top of the IC chips

ABSTRACT

A new method is provided for the creation of interconnect lines. Fine line interconnects are provided in a first layer of dielectric overlying semiconductor circuits that have been created in or on the surface of a substrate. A layer of passivation is deposited over the layer of dielectric, a thick second layer of dielectric is created over the surface of the layer of passivation. Thick and wide interconnect lines are created in the thick second layer of dielectric. The first layer of dielectric may also be eliminated, creating the wide thick interconnect network on the surface of the layer of passivation that has been deposited over the surface of a substrate.

This application is a continuation of application Ser. No. 12/019,635,filed on Jan. 25, 2008, now U.S. Pat. No. 7,928,576, which is acontinuation of application Ser. No. 11/788,221, filed on Apr. 19, 2007,now U.S. Pat. No. 7,459,790, which is a continuation of application Ser.No. 10/685,872, filed on Oct. 15, 2003, now U.S. Pat. No. 7,230,340.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to the fabrication of integrated circuit devices,and more particularly, to a method of post-passivation processing forthe creation of conductive interconnects.

2. Description of the Prior Art

Improvements in semiconductor device performance are typically obtainedby scaling down the geometric dimensions of the Integrated Circuits;this results in a decrease in the cost per die while at the same timesome aspects of semiconductor device performance are improved. The metalconnections which connect the Integrated Circuit to other circuit orsystem components become of relative more importance and have, with thefurther miniaturization of the IC, an increasingly negative impact onthe circuit performance. The parasitic capacitance and resistance of themetal interconnections increase, which degrades the chip performancesignificantly. Of most concern in this respect is the voltage drop alongthe power and ground buses and the RC delay of the critical signalpaths. Attempts to reduce the resistance by using wider metal linesresult in higher capacitance of these wires.

To solve this problem, one approach has been to develop low resistancemetal (such as copper) for the wires while low-k dielectric materialsare used in between signal lines. Current practice is to create metalinterconnection networks under a layer of passivation. This approach,however, limits the interconnect network to fine line interconnects andthe therewith associated high parasitic capacitance and high lineresistivity. The latter two parameters, because of their relatively highvalues, degrade circuit performance, an effect which becomes even moresevere for higher frequency applications and for long interconnect linesthat are, for instance, used for clock distribution lines. Also, fineline interconnect metal cannot carry high values of current that istypically needed for ground busses and for power busses.

It has previously been stated that it is of interest to thesemiconductor art to provide a method of creating interconnect linesthat removes typical limitations that are imposed on the interconnectwires, such as unwanted parasitic capacitances and high interconnectline resistivity. U.S. Pat. No. 6,383,916 to the same assignee as thepresent invention provides such a method. An analogy can be drawn inthis respect whereby the currently (prior art) used fine-lineinterconnection schemes, which are created under a layer of passivation,are the streets in a city; in the post-passivation interconnectionscheme of the above patent, the interconnections that are created abovea layer of passivation can be considered the freeways between cities.

FIG. 1 shows a diagram of a silicon substrate on the surface of whichhas been created a conductive interconnect network. The structure thatis shown in FIG. 1 addresses prior art power and ground distributionnetworks. The various features that have been highlighted in FIG. 1 arethe following:

-   -   40, a silicon substrate on the surface of which has been created        an interconnect network    -   42, a sample number of semiconductor circuits that have been        created in or on the surface of the substrate 40    -   44, two electrostatic discharge (ESD) circuits created in or on        the surface of the substrate 40; one ESD circuit is provided for        each pad that is accessible for external connections (pads 52,        see below)    -   46 is a layer of interconnect lines; these interconnect lines        are above the surface of substrate 40 and under the layer 48 of        passivation and represent a typical application of prior art        fine-line interconnects; these fine-line interconnects of layer        46 typically have high resistivity and high parasitic        capacitance.    -   48 is a layer of passivation that is deposited over the surface        of the layer 46 of interconnect lines. The passivation layer is        the final layer of the IC process in the prior art. The        passivation layer is used to protect the underlying devices and        fine-line interconnection from damage by mobile ions, moisture,        transition metals, and contamination.    -   50 is a power or ground bus that connects to the circuits 42 via        fine-line interconnect lines provided in layer 46; this power or        ground bus is typically of wider metal since this power or        ground bus carries the accumulated current or ground connection        for the devices 42. The power, ground buses are built in the        fine line interconnect under the passivation layer. The fine        line interconnection can be in one layer or more than one layer        of metals.    -   52 is a power or ground pad that passes through the layer 48 of        passivation and that has been connected to the power or ground        bus 50.

From the above the following can be summarized: circuits are created inor on the surface of a silicon substrate, interconnect lines are createdfor these circuits for further interconnection to external circuitry,the circuits are, on a per I/O pad basis, provided with an ESD circuit;these circuits with their ESD circuit are connected to a power or groundpad that penetrates a layer of passivation. The layer of passivation isthe final layer that overlies the created interconnect line structure;the interconnect lines underneath the layer of passivation are fine lineinterconnects and have all the electrical disadvantages of fine lineinterconnects such as high resistivity and high parasitic capacitance.

Relating to the diagram that is shown in FIG. 1, the following commentapplies: ESD circuits are, as is known in the art, provided for theprotection of semiconductor circuits against unwanted electrostaticdischarge. For this reason, each pad that connects a semiconductorcircuit to the external circuits must be provided with an ESD circuit.

FIG. 2 shows a diagram of a prior art configuration that resembles thediagram shown in FIG. 1. The structure that is shown in FIG. 2 howeverrelates to clock and signal distribution networks. FIG. 2 shows inaddition (to the previously highlighted aspects of FIG. 1):

-   -   45 are two ESD circuits that are provided in or on the surface        of the substrate 40; ESD circuits are always required for any        external connection to an input/output (I/O) pad.    -   45′ which are circuits that can be receiver or driver or I/O        circuits for input (receiver) or output (driver) or I/O purposes        respectively.    -   54 is a clock, signal, address, or data bus built in the fine        line interconnection metal under the passivation layer. The        clock, signal, or buses can be in one layer or in more than one        layer of fine line interconnect metals.    -   56 is a clock or signal pad that has been extended through the        layer 48 of passivation.

The same comments apply to the diagram that is shown in FIG. 2 aspreviously have been made with respect to FIG. 1, with as a summarystatement that the layer of passivation is the final layer that overliesthe created structure, the interconnect lines underneath the layer ofpassivation are fine line interconnects and have all the electricaldisadvantages of fine line interconnects such as high resistivity andhigh parasitic capacitance.

Further with respect to FIG. 2 where pads 56 are signal or clock pads:

-   -   pads 56 must be connected to ESD and driver/receiver or I/O        circuits 45    -   for signal or clock pads 56, these pads must be connected not        only to ESD circuits but also to driver or receiver or I/O        circuits, highlighted as circuit 45′ in FIG. 2    -   after (clock and signal) stimuli have passed through the ESD and        driver/receiver or I/O circuits, these stimuli are further        routed using, under prior art methods, fine-line interconnect        wires. A layer of passivation is deposited over the dielectric        layer in which the interconnect network has been created.

It is therefore of interest to the semiconductor art to provide a methodof creating interconnect lines that removes typical limitations that areimposed on the interconnect wires, such as unwanted parasiticcapacitances and high interconnect line resistivity. The presentinvention is related to U.S. Pat. No. 6,303,423, to the same assignee asthe present invention.

SUMMARY OF THE INVENTION

A principal objective of the invention is to provide a method for thecreation of interconnect metal that allows for the use of thick and widemetal.

Another objective of the invention is to provide a method for thecreation of interconnect metal that uses the application of a thicklayer of dielectric such as polymer.

Yet another objective of the invention is to provide a method thatallows for the creation of long interconnect lines, whereby these longinterconnect lines do not have high resistance or introduce highparasitic capacitance.

A still further objective of the invention is to create interconnectlines that can carry high levels of current for the creation of powerand ground distribution networks.

A still further objective of the invention is to create interconnectmetal that can be created using cost effective methods of manufacturingby creating the interconnect metal on the surface of and after a layerof passivation has been deposited.

In accordance with the objectives of the invention a new method isprovided for the creation of interconnect lines. Fine line interconnectsare provided in a first layer of dielectric overlying semiconductorcircuits that have been created in or on the surface of a substrate. Alayer of passivation is deposited over the layer of dielectric; a thicksecond layer of dielectric is created over the surface of the layer ofpassivation. Thick and wide interconnect lines are created in the thicksecond layer of dielectric. Intra-chip drivers are connected to thethick, wide post-passivation interconnections.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a representation of a silicon substrate over which a prior artfine-line interconnect network is created over which a layer ofpassivation is deposited, and power and/or ground pads are providedthrough the layer of passivation for external connection. The structurethat is shown in FIG. 1 addresses prior art power and grounddistribution networks.

FIG. 2 is a representation of a silicon substrate over which a prior artfine-line interconnect network is created over which a layer ofpassivation is deposited, and clock and/or signal pads are providedthrough the layer of passivation for external connection. The structurethat is shown in FIG. 2 addresses prior art clock and signaldistribution networks.

FIG. 3 a is a representation of a silicon substrate over which aninterconnect network is created according to the invention. Power and/orground pads are provided for external connection. The structure that isshown in FIGS. 3 a and 3 b relates to power and ground distributionnetworks of the invention. 66 represents one or more than one layer ofmetal.

FIG. 3 b further distributes the power and ground to the circuit nodesthrough power and ground distribution lines that are below a layer ofpassivation and power and ground distribution lines that are above alayer of passivation. 66 and 66′ each represent one or more than onelayer of metal.

FIG. 3 c shows an alternative wherein contact is made to a conventionalbond pad through the passivation layer rather than through apost-passivation thick wide metal system.

FIG. 4 a is a representation of a silicon substrate over which aninterconnect network is created according to the invention. An ESDand/or driver and/or receiver circuit access pad is provided through thesurface of the layer of dielectric for external connection. Thestructure that is shown in FIGS. 4 a and 4 b address clock and signaldistribution networks of the invention. “Signals” refer to, but are notlimited to, address and data. 72 in the figure represents one or morethan one layer of metal.

FIG. 4 b further distributes signal and clock to the circuit nodesthrough clock and signal distribution lines that are below a layer ofpassivation in addition to clock and signal distribution lines that areabove a layer of passivation. 71 and 71′ each represent one or more thanone layer of metal.

FIGS. 4 c and 4 d show smaller intra-chip circuit drivers.

FIG. 5 a is a representation of a silicon substrate over which aninterconnect network is created according to the invention. No I/Oconnect pad is provided for external connection in specific networks.The structure that is shown in FIGS. 5 a and 5 b addresses clock andsignal distribution networks of the invention.

FIG. 5 b differentiates between clock and signal distribution lines thatare below a layer of passivation and clock and signal distribution linesthat are above a layer of passivation.

FIGS. 5 c and 5 d show smaller intra-chip circuit drivers.

FIGS. 6 a and 6 b are representations of the interconnect structure ofthe present invention.

FIGS. 6 c and 6 d are representations of the interconnect structure ofthe present invention including wirebonding.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

U.S. Pat. No. 6,383,916 teaches an Integrated Circuit structure wherere-distribution and interconnect metal layers are created in layers ofdielectric over the passivation layer of a conventional IntegratedCircuit (IC). A layer of passivation is deposited over the IC, a thicklayer of polymer is alternately deposited over the surface of the layerof passivation, and thick, wide metal lines are formed over thepassivation.

Referring now more specifically to FIG. 6 a, there is shown a crosssection of one implementation of U.S. Pat. No. 6,383,916. The surface ofsilicon substrate 10 has been provided with transistors 11 and otherdevices (not shown in FIG. 6 a). The surface of substrate 10 is coveredby an interlevel dielectric (ILD) layer 12, formed over the devices.

Layers 14 (two examples are shown) represent all of the metal layers anddielectric layers that are typically created on the dielectric layer 12.Layers 14 contain multiple layers of dielectric or insulation and thelike; conductive interconnect lines 13 make up the network of electricalconnections that are created throughout layers 14. Overlying and on thesurface of layers 14 are points 16 of electrical contact. These points16 of electrical contact can, for instance, be bond pads that establishelectrical interconnects to external circuits. These points of contact16 can be points of interconnect within the IC arrangement thatestablish electrical interconnects to the transistors and other devicesin the surface of the substrate. A passivation layer 18, formed of, forexample, a composite layer of silicon oxide and silicon nitride (thethickness of silicon nitride is usually thicker than 0.4 μm for thepassivation purpose), is deposited over the surface of layers 14, andfunctions to prevent the penetration of mobile ions (such as sodiumions), moisture, transition metals (such as gold, copper, silver), andother contamination. The passivation layer is used to protect theunderlying devices (such as transistors, polysilicon resistors,poly-to-poly capacitors, etc.) and the fine-line metal interconnection.

The key steps of U.S. Pat. No. 6,383,916 begin with the deposition of athick layer 20 of a polymer, preferably polyimide, that is depositedover the surface of passivation layer 18. Access must be provided topoints of electrical contact 16; for this reason a pattern of openingsis formed through the polyimide layer 20 and the passivation layer 18.Contact points 16 are, by means of the openings that are created in thelayer 20 of polyimide, electrically extended to the surface of layer 20.

After formation of the openings, metallization is performed to createpatterned wide metal layers 24 and 25 and to connect to contact points16. Lines 24 and 25 can be of any design in width and thickness toaccommodate specific circuit design requirements. This structure allowsfor the interconnection of circuit elements at various distances usingthe thick, wide (as compared to the underlying “fine line” metallizationin layers 14) metal of 25. Thick, wide metal 25 has smaller resistanceand capacitance than the fine line metal 14 and is also easier and morecost effective to manufacture. The thick, wide metals, usually formed byphotoresist defined electroplating, are electroplated metals. Gold andcopper are preferred. Optionally, a layer of polymer (not shown in FIG.6 a) can also be formed to encapsulate the thick, wide metal 25.

Referring now to FIG. 6 b, multiple layers of post-passivation metalscan also be built for some applications. A second layer of polymer 21 isdeposited and patterned, followed by the formation of the second layerof thick, wide metal 26, 27. Co-pending U.S. patent applicationMSL98-002CCC-CIP, Ser. No. 10/154,662, filed on May 24, 2002, and hereinincorporated by reference, provides details of the formation of themetal layers. A final encapsulation 22 covers the whole wafer with someexposed pads 28 for connection to external circuits.

FIGS. 6 c and 6 d are analogous to FIGS. 6 a and 6 b, respectively, butshow the process of the invention in conjunction with wirebonding.Openings 29 have been made to aluminum pad 16. Conventional wirebondingtechniques may be use to form wirebond connections to the originalAluminum pad 16 exposed by openings 29 in FIGS. 6 c and 6 d. Here, apiece of aluminum or damascene copper is used for a short distanceinterconnection between wirebonding pads and the post-passivationinterconnection.

The following comments relate to the size and the number of the contactpoints 16 in FIGS. 6 a-6 d. Because these contact points 16 are locatedon top of a thin dielectric (layer 14, FIGS. 6 a-6 d) the pad sizecannot be too large since a large pad size brings with it a largecapacitance. In addition, a large pad size will interfere with therouting capability of that layer of metal. It is therefore preferred tokeep the size of the pad 16 relatively small. The size of the contactpad 16 can be in the order of 0.5 μm to 40 μm, the exact size beingdependent on the electrical requirements of the contacts.

The referenced application does not impose a limitation on the number ofcontact pads that can be included in the design; this number is not onlydependent on package design requirements but is mostly dependent on theinternal circuit design requirements. Layer 18 in FIGS. 6 a-6 d can be atypical IC passivation layer.

The most frequently used passivation layer in the present state of theart is plasma enhanced CVD (PECVD) oxide and nitride. In creating layer18 of passivation, a layer of approximately 0.5 μm PECVD oxide can bedeposited first followed by a layer of approximately more than 0.4 μmnitride. Passivation layer 18 is very important because it protects thedevice wafer from moisture and foreign ion contamination. To achieve thepassivation purpose, the silicon nitride is usually thicker than 0.4 μm.The positioning of this layer between the sub-micron process (of theintegrated circuit) and the tens-micron process (of the interconnectingmetalization structure) is of critical importance since it allows for acheaper process that possibly has less stringent clean room requirementsfor the process of creating the interconnecting metalization structure.

Layers 20, 21, and 22 are a thick polymer dielectric layer (for examplepolyimide) that have a thickness in excess of 2 μm (after curing). Therange of the polymer thickness can vary from 2 μm to 150 μm, dependenton electrical design requirements.

For the deposition of layers 20, 21, 22 the Hitachi-Dupont polyimide HD2732 or 2734 or Asahi polyimide LS800, I-83005, or 8124, can, forexample, be used. The polyimide can be spin-on coated and cured. Afterspin-on coating, the polyimide will be cured at 370 degrees C. for 1hour in a vacuum or nitrogen ambient. For thicker polyimide, thepolyimide film can be multiple coated and cured. The polyimide also canbe formed by screen printing.

Another material that can be used to create layers 20, 21, 22 is thepolymer benzocyclobutene (BCE). This polymer is at this timecommercially produced by for instance Dow Chemical and has recentlygained acceptance to be used instead of typical polyimide application.

The thick layers 20, 21, 22 of polymer can be coated in liquid form onthe surface of the layer 18 of passivation or it can be laminated overthe surface of layer 18 or passivation by dry film application.

Additional electrical components such as an inductor, a capacitor, andthe like, not shown, can be created on the surface of layer 20 or 22 ofpolyimide and in electrical contact with underlying metallization.

Now, the process of the present invention will be described in detail.Referring now specifically to FIG. 3 a, this figure refers to power andground architecture. There is shown in FIG. 3 a a silicon substrate 40over which an interconnect network is created according to theinvention, with a wide and thick wire interconnect network created in athick layer of dielectric overlying a layer of passivation. A powerand/or ground pad can be provided for external connection. Following arethe various features that are shown in FIG. 3 a:

-   -   40 is the silicon substrate on the surface of which interconnect        lines are created in accordance with the invention.    -   42 are semiconductor circuits that are created in or on the        surface of substrate 40. Each semiconductor circuit has several        nodes connected to other circuits or power/ground.    -   43 is the power or ground node of the semiconductorcircuits 42.    -   44 is an ESD circuit that is provided for the protection of        circuits 42.    -   58 is a layer including the semiconductor devices 42 that have        been created in or on the surface of substrate 40.    -   60 are one or more dielectric layers that have been created        overlying the layer 58 including the semiconductor devices 42.    -   61 is a connection comprising metal formed through a via through        one or more dielectric layers 60; more such vias are shown in        FIG. 3 a but are, for reasons of simplicity, not highlighted.    -   62 is a layer of passivation that has been deposited overlying        the layer 60.    -   63 is one of the vias that passes through layer 62 of        passivation; more such vias are shown in FIG. 3 a but are, for        reasons of simplicity, not highlighted.    -   64 is a layer of dielectric in which, as a post-passivation        process, interconnects have been created.    -   65 is a power or ground bus that is connected to the ESD circuit        44, originating in layer 64 and further passing through layers        62 and 60. This connection comprises metal formed through vias        in the dielectric layers 62 and 60.    -   66 is the power or ground bus for the connection scheme in layer        64. This power or ground bus 66 could be one or more than one        thick, wide metal layers in dielectric layer 64 including a        polymer. For multiple layers of metal, the metals are connected        through vias in the polymer.    -   67 is a via that is created overlying the layer 62 of        passivation and in the dielectric layer 64; more such vias are        shown in FIG. 3 a but are, for reasons of simplicity, not        highlighted.    -   68 is the power or ground pad for the multiple semiconductor        devices 42 in layer 58.

From the representation that is shown in FIG. 3 a, it is clear that,most importantly, the ability to create interconnects to semiconductordevices 42 that have been created in or on the surface of a substrate 40has been extended by creating these interconnects not only as fine-lineinterconnects 61 in layer 60 but extending the interconnect by creationof a wide, thick wire interconnect network 66 overlying a layer ofpassivation 62. This provides immediate and significant benefits in thatthese lines are further removed from the surface of the substrate 40(reducing parasitic influences by the interconnect lines on thesemiconductor devices 42 that are created in or on the surface of thesubstrate 40) while the interconnect network 66 that is createdoverlying the layer of passivation 62 can now contain sturdier; that is,thicker and wider, interconnect lines. The thick, wide metalinterconnects 66 can be used for power and ground distribution; thisdistribution then takes place above a layer of passivation 62 andpartially replaces and extends the conventional method of having forthese purposes a fine-line distribution interconnect network under thelayer of passivation 62.

Some points of interest can be listed at this time as they relate toprior art methods and to the invention.

PRIOR ART

-   -   provides an ESD circuit for each pad that is used for external        input/output interconnect    -   provides a fine-line interconnect network for further        distribution of the power and ground stimuli, and    -   the fine-line power and ground distribution network is created        underneath a layer of passivation.

In this respect and related to the above provided comments, it must beremembered that power and ground pads do not require drivers and/orreceiver circuitry.

The Invention:

-   -   does not need to create an ESD circuit for each pad that is used        for external input/output interconnect, in view of the more        robust wiring that is connected to the ESD circuit, resulting in        reduced power loss and resulting in more power being delivered        to the ESD circuit, and    -   allows for the power and ground interconnects to be directly        connected to the power and ground nodes of the internal circuits        of a semiconductor device, this either without an ESD circuit or        with a smaller than regular ESD circuit (as previously        explained).

The method that is used to create the interconnect network that is shownin FIG. 3 a addresses only the use of power and ground connections. FIG.3 a can be summarized as follows: a silicon substrate 40 is provided inthe surface of which there have been created semiconductor devices 42and at least one electrostatic discharge (ESD) circuit 44; a one or morelayers 60 of dielectric are deposited over the substrate 40; a fine-lineinterconnect network 61 is created in the dielectric layers 60 makingcontact with the active circuits 42 and the ESD circuit 44. A layer ofpassivation 62 is deposited over the fine-line interconnect network 61.Openings are created in the layer of passivation 62 that aligns withpoints of contact in the top layer of the fine-line interconnect network61. A thick layer of dielectric 64 is optionally deposited over thelayer of passivation 62; a wide thick line interconnect network 66 iscreated in the layer of dielectric 64, and connected to the ESDcircuits. A point of electrical contact 68 comprising a power or groundcontact is provided in the surface of the thick layer 64 of dielectric.

FIG. 3 b provides further insight into the creation of the power andground interconnect lines of the invention whereby these interconnectlines have been shown as interconnect lines 66 and interconnect lines66′. Interconnect lines 66 have been created above the layer 62 ofpassivation and act as global power and ground interconnect lines.Interconnect lines 66′ have been created below the layer 62 ofpassivation and act as local power and ground interconnect lines.

FIG. 3 c provides an alternative in which contact is made to aconventional aluminum metal 61′, for example, through the passivationlayer 62 rather than making contact to the post-passivation thick, widemetal system 66. The top layer of metal 61′ is used for wirebondingpurposes and for connection between wirebonding pads and the wide, thickinterconnect lines 66. The distance of 61′ is a short distance; forexample, <500 μm in length.

In the process of the present invention, in all aspects shown in thefigures, the post passivation metallization 66 can optionally beperformed directly on the passivation layer 62 without the interveningpolymer layer. Although the polymer layer provides distinct advantages,it may be desirable to dispense with the polymer layer in order to savecosts.

Referring now to FIG. 4 a, FIG. 4 a addresses the interconnections ofsignal and clock line. Signal here includes address, data, logic, andanalog signals. Signal also includes the power/ground voltage outputfrom voltage regulators. In FIG. 4 a there is shown a cross section of asilicon substrate 40 over which an interconnect network 61 is createdaccording to the invention. An access pad 70 to an ESD circuit 45 ordriver or receiver circuits or I/O circuits 45′ is provided through thelayers 64 and 60 of dielectric for external connection. While an ESDcircuit 45 is required for all circuits 42 to which an I/O connection isestablished, the I/O connection can also be provided to a receivercircuit or a driver circuit or an I/O circuit 45′.

The features not previously highlighted that are shown in FIG. 4 a are:

-   -   the invention provides an interconnect network 72 comprising        wide, thick interconnect lines for distribution of the clock and        signal stimuli,    -   the invention creates an interconnect network 72 of thick, wide        interconnect lines for the clock and signal stimuli overlying a        layer of passivation 62,    -   70 is an external connection (pad) that is provided for the ESD        circuit 45 and for driver/receiver/I/O circuit 45′; pad 70        provides external access for clock and signal stimuli to        circuits 45 and 45′, and    -   72 is a clock or signal bus that is created in the dielectric        layer 64 using thick, wide wires for interconnect lines; it must        be noted that the clock and signal interconnect line        distribution 72 is entirely contained within the layer 64        without providing an external point of I/O interconnect.

The method that is used to create the interconnect network that is shownin cross section in FIG. 4 a can be summarized as follows. A siliconsubstrate 40 is provided; active circuits have been created in thesurface of the substrate 40 including an ESD circuit 45 and thereceiver, driver and I/O circuit 45′. First layers 60 of dielectric ofinorganic material are deposited over the substrate 40 and a fine-lineinterconnect network 61 is created in the layers 60 of dielectric,making contact with the active circuitry 45, 45′, and 42. A layer 62 ofpassivation is deposited over the first thin layers 60 of dielectric; apattern 63 of metal plugs is created in the layer 62 of passivation (or,for low aspect ratio openings, direct contact is established betweenoverlying layers 72 of metal through an opening in an interposed layer64 of dielectric); the metal interconnects 67 align with points ofelectrical contact in the surface of the first layers 60 of dielectric.One or more thicker layers 64 of dielectric are deposited over thesurface of the layer 62 of passivation, typically of an organicmaterial; a wide thick line interconnect network 72 is created in thethicker layer 64 of dielectric, making electrical contact with the metalplugs or the metal pads in or under the layer 62 of passivationconnected to the receiver, driver or I/O circuit 45′. A point ofelectrical contact 70 is provided in the surface of the second layer 64of dielectric and connected to the ESD circuit 45 and the receiver,driver or I/O circuit 45′.

FIG. 4 b provides further insight into the creation of the signal andclock interconnect lines of the invention whereby these interconnectlines have been shown as interconnect lines 71 and interconnect lines71′. Interconnect lines 71 have been created above the layer 62 ofpassivation and act as global signal and clock interconnect lines.Interconnect lines 71′ have been created below the layer 62 ofpassivation and act as local signal and clock interconnect lines.Furthermore, internal circuits 42 have no driver, no receiver, and noESD connections.

Intra-chip drivers and receivers 80 may be necessary if theinterconnection distance is long and/or the load of the net of circuits42 is large, as shown in FIGS. 4 c and 4 d. A driver circuit is used todrive a load; i.e., to drive current. A driver current is the output ofa driver circuit. The ability to drive current is proportional, in CMOSdevices, to the W/L ratio, where W/L is the ratio of the device channelwidth to its length. These intra-chip drivers 80 are typically smallerthan I/O drivers 45′. Intra-chip circuits 80 typically have no ESDcircuits and no I/O circuits. For short distance on-chipinterconnection, no intra-chip circuits may be required. FIG. 4 c showsan interconnecting structure 72 connecting multiple intra-chip driversor receivers 80, which are connected in series to the internal circuits42. FIG. 4 d shows an example of internal circuits 42 that need toutilize attached intra-chip drivers or receivers while internal circuits42′ do not require attached intra-chip drivers or receivers. Also shownin FIG. 4 d is an interconnecting structure 71 connecting multipleintra-chip drivers or receivers 80, which are connected in series to theinternal circuits 42.

Further provided are:

-   -   45 are two ESD circuits that are provided in or on the surface        of the substrate 40, as shown in FIGS. 4 a-4 d; ESD circuits are        always required for any external connection to an input/output        (I/O) pad    -   45′ which are circuits that can be receiver or driver or I/O        circuits for input (receiver) or output (driver) or I/O purposes        respectively, as shown in FIGS. 4 a-4 d. These are off-chip        drivers or receivers or I/O circuits.

Intra-chip circuits 80 are usually smaller than the off-chip drivers45′. The intra-chip driver circuits 80 are different from the off-chipcircuits 45′ in that they have no I/O circuits and no ESD circuits.FIGS. 4 c and 4 d show smaller internal driver circuits 80 connected tothe internal circuits 42. 45′ are larger off-chip circuits.

FIG. 5 a shows a representation of a silicon substrate 40 over which aninterconnect network 74 is created according to the invention, with theinterconnect network 74 created in a thick layer 64 of dielectricoverlying a layer 62 of passivation. No ESD circuit, receiver, driver orI/O circuit access pad is provided for external connection to theinternal circuits 42. Shown in FIG. 5 a and not previously highlightedis the clock or signal interconnect line 74, providing for aninterconnect scheme of thick, wide lines overlying a passivation layer62 whereby no external I/O connections are provided. Due to the thick,wide lines of the interconnect network 74 that is created overlying apassivation layer 62, the clock and signal distribution can take placeentirely within the dielectric layer 64; this as opposed to prior artmethods where, for clock and signal distribution lines, each thick, wideinterconnect line (where such thick, wide interconnect lines are used)must be provided with at least one I/O connect point for off-chipconnection.

The method that is used to create the wide thick line interconnect lines74 that is shown in cross section in FIG. 5 a can be summarized asfollows and is similar to that described above for FIG. 4 a. A siliconsubstrate 40 is provided. Active devices have been provided in thesurface of the substrate. First thin layers 60 of dielectric aredeposited over the surface of the substrate 40, a fine-line interconnectnetwork 61 is created in the first layers 60 of dielectric, comprisingfine-line interconnect lines, making contact with points of electricalcontact in the surface of the substrate 40. A layer 62 of passivation isdeposited over the surface of the first layers 60 of dielectric, apattern of conductive interconnects 63 is created in the layer 62 ofpassivation and aligns with the points of electrical contact in thesurface of the first layer 60 of dielectric. One or more second layers65 of dielectric are deposited over the surface of the layer 62 ofpassivation, the interconnecting structure 74 making electrical contactwith the conductive interconnects 63 in the layer 62 of passivation.FIG. 5 a shows a series of driver/receivers, or transceivers, orrepeater devices 103 each comprising a receiver 101 and a driver 102.Receivers 101 are connected to drivers 102.

FIG. 5 b provides further insight into the creation of the signal andclock interconnect lines of the invention whereby these interconnectlines have been shown as interconnect lines 71 and interconnect lines71′. Interconnect lines 71 have been created above the layer 62 ofpassivation and can act as global signal and clock interconnect lines.Interconnect lines 71′ have been created below the layer 62 ofpassivation and act as local signal and clock interconnect lines. Alsoas shown in FIG. 5 b, internal circuits 42 are shown. Circuits 42 haveno I/O circuits and no ESD circuits. FIGS. 5 c and 5 d show smallerinternal driver circuits 80 connected to the internal circuits 42. FIGS.5 c and 5 d show an interconnecting structure 74 connects multipleintra-chip drivers or receivers 80, which are connected in series to theinternal circuits 42.

It must further be emphasized that, where FIGS. 3-5 show a fine-lineinterconnect network 61 that underlies the layer 62 of passivation, theinvention also enables and can be further extended with the completeelimination of the fine-line interconnect network 61 and creating aninterconnect network in the dielectric layer 64 that uses only thick,wide wires. For this application of the invention, the first layer ofdielectric 60 is not applied, the layer 62 of passivation is depositeddirectly over the surface of the created semiconductor devices 58 in oron the surface of substrate 40.

It is further of value to briefly discuss the above implemented andaddressed distinction between fine-line interconnect lines and wide,thick interconnect lines. The following points apply in this respect:

-   -   the prior art fine line interconnect lines are created        underneath a layer of passivation, the wide, thick interconnect        lines of the invention are created above a layer of passivation    -   the fine-line interconnect lines are typically created in a        layer of inorganic dielectric, the thick wide interconnect lines        are typically created in a layer of dielectric comprising        polymer. This is because an inorganic material cannot be        deposited as a thick layer of dielectric because such a layer of        dielectric could develop fissures and crack as a result.        Although the polymer is preferred, the thick wide interconnect        lines could be formed over a conventional passivation layer        without the polymer.    -   fine-line interconnect metal is typically created using methods        of sputter with resist etching or of damascene processes using        oxide etch with electroplating after which CMP is applied.        Either one of these two approaches cannot create thick metal due        to cost considerations or oxide cracking    -   thick, wide interconnect lines can be created by first        sputtering a thin metal base layer, coating and patterning a        thick layer of photoresist, applying a thick layer of metal by        electroplating, removing the patterned photoresist and        performing metal base etching (of the sputtered thin metal        base). This method allows for the creation of a pattern of very        thick metal; metal thickness in excess of 1 μm can in this        manner be achieved while the thickness of the layer of        dielectric in which the thick metal interconnect lines are        created can be in excess of 2 μm.

In summary, the post-passivation interconnection of the presentinvention can connect to three types of circuits (i) off-chip drivers,receivers, I/O circuits, and ESD circuits, (ii) intra-chip drivers andreceivers, and (iii) internal circuits. No driver is required forfreeway interconnection with a distance<“D”. A smaller driver is usedfor freeway interconnection with a distance>“D”; that is, intra-chipconnection. For I/O and ESD circuits, a large driver, larger than theintra-chip driver, is used for off-chip connection.

Although the invention has been described and illustrated with referenceto specific illustrative embodiments thereof, it is not intended thatthe invention be limited to those illustrative embodiments. Thoseskilled in the art will recognize that variations and modifications canbe made without departing from the spirit of the invention. It istherefore intended to include within the invention all such variationsand modifications which fall within the scope of the appended claims andequivalents thereof.

What is claimed is:
 1. A chip comprising: a silicon substrate; a firstdielectric layer over said silicon substrate; a first interconnectingstructure over said silicon substrate and in said first dielectriclayer; a second interconnecting structure over said silicon substrateand in said first dielectric layer; an insulating layer over saiddielectric layer; a third interconnecting structure over said insulatinglayer, wherein said first interconnecting structure is connected to saidsecond interconnecting structure through said third interconnectingstructure, wherein a top surface of said third interconnecting structurehas no access for external connection, wherein a power is adapted to beprovided to said third interconnecting structure, wherein said thirdinterconnecting structure is provided by a topmost metal layer ofinterconnecting lines of said chip.
 2. The chip of claim 1, wherein saidpower is output from a voltage regulator.
 3. The chip of claim 1,wherein said insulating layer comprises a nitride.
 4. The chip of claim1, wherein said insulating layer comprises silicon nitride.
 5. The chipof claim 1, wherein said insulating layer comprises an oxide.
 6. Thechip of claim 1, wherein said insulating layer comprises silicon oxide.7. The chip of claim 1, wherein said first interconnecting structurecomprises an electroplated metal.
 8. The chip of claim 1, wherein saidfirst interconnecting structure comprises a damascene metal.
 9. The chipof claim 1, wherein said third interconnecting structure comprisescopper.
 10. The chip of claim 1, wherein said third interconnectingstructure comprises gold.
 11. The chip of claim 1 further comprising athird dielectric layer over said insulating layer, wherein said thirddielectric layer comprises a portion on said top surface of said thirdinterconnecting structure.
 12. The chip of claim 11, wherein said thirddielectric layer comprises a polymer.
 13. The chip of claim 1 furthercomprising a third dielectric layer over said insulating layer, whereinsaid third dielectric layer comprises a portion between said thirdinterconnecting structure and said insulating layer, wherein said thirddielectric layer comprises a polymer.
 14. A chip comprising: a siliconsubstrate; a first dielectric layer over said silicon substrate; a firstinterconnecting structure over said silicon substrate and in said firstdielectric layer; a second interconnecting structure over said siliconsubstrate and in said first dielectric layer; an insulating layer oversaid dielectric layer; and a third interconnecting structure over saidinsulating layer, wherein said first interconnecting structure isconnected to said second interconnecting structure through said thirdinterconnecting structure, wherein a top surface of said thirdinterconnecting structure has no access for external connection, whereina ground is adapted to be provided to said third interconnectingstructure, wherein said third interconnecting structure is provided by atopmost metal layer of interconnecting lines of said chip.
 15. The chipof claim 14, wherein said insulating layer comprises a nitride.
 16. Thechip of claim 14, wherein said insulating layer comprises siliconnitride.
 17. The chip of claim 14, wherein said insulating layercomprises an oxide.
 18. The chip of claim 14, wherein said insulatinglayer comprises silicon oxide.
 19. The chip of claim 14, wherein saidfirst interconnecting structure comprises an electroplated metal. 20.The chip of claim 14, wherein said first interconnecting structurecomprises a damascene metal.
 21. The chip of claim 14, wherein saidthird interconnecting structure comprises copper.
 22. The chip of claim14, wherein said third interconnecting structure comprises gold.
 23. Thechip of claim 15 further comprising a third dielectric layer over saidinsulating layer, wherein said third dielectric layer comprises aportion on said top surface of said third interconnecting structure. 24.The chip of claim 23, wherein said third dielectric layer comprises apolymer.
 25. The chip of claim 14 further comprising a third dielectriclayer over said insulating layer, wherein said third dielectric layercomprises a portion between said third interconnecting structure andsaid insulating layer, wherein said third dielectric layer comprises apolymer.
 26. A chip comprising: a silicon substrate; a first dielectriclayer over said silicon substrate; a first interconnecting structureover said silicon substrate and in said first dielectric layer; a secondinterconnecting structure over said silicon substrate and in said firstdielectric layer; a passivation layer over said first dielectric layer;and a third interconnecting structure over said passivation layer,wherein said first interconnecting structure is connected to said secondinterconnecting structure through said third interconnecting structure,wherein a top surface of said third interconnecting structure has noaccess for external connection, wherein a power is adapted to beprovided to said third interconnecting structure.
 27. The chip of claim26, wherein said power is output from a voltage regulator.
 28. The chipof claim 26, wherein said passivation layer comprises a nitride.
 29. Thechip of claim 26, wherein said passivation layer comprises siliconnitride.
 30. The chip of claim 26, wherein said passivation layercomprises an oxide.
 31. The chip of claim 26, wherein said passivationlayer comprises silicon oxide.
 32. The chip of claim 26, wherein saidfirst interconnecting structure comprises an electroplated metal. 33.The chip of claim 26, wherein said first interconnecting structurecomprises a damascene metal.
 34. The chip of claim 26, wherein saidthird interconnecting structure comprises copper.
 35. The chip of claim26, wherein said third interconnecting structure comprises gold.
 36. Thechip of claim 26 further comprising a third dielectric layer over saidpassivation layer, wherein said third dielectric layer comprises aportion on said top surface of said third interconnecting structure. 37.The chip of claim 36, wherein said third dielectric layer comprises apolymer.
 38. The chip of claim 26 further comprising a third dielectriclayer over said passivation layer, wherein said third dielectric layercomprises a portion between said third interconnecting structure andsaid passivation layer, wherein said third dielectric layer comprises apolymer.
 39. A chip comprising: a silicon substrate; a first dielectriclayer over said silicon substrate; a first interconnecting structureover said silicon substrate and in said first dielectric layer; a secondinterconnecting structure over said silicon substrate and in said firstdielectric layer; a passivation layer over said first dielectric layer;and a third interconnecting structure over said passivation layer,wherein said first interconnecting structure is connected to said secondinterconnecting structure through said third interconnecting structure,wherein a top surface of said third interconnecting structure has noaccess for external connection, wherein a ground is adapted to beprovided to said third interconnecting structure.
 40. The chip of claim39, wherein said passivation layer comprises a nitride.
 41. The chip ofclaim 39, wherein said passivation layer comprises silicon nitride. 42.The chip of claim 39, wherein said passivation layer comprises an oxide.43. The chip of claim 39, wherein said passivation layer comprisessilicon oxide.
 44. The chip of claim 39, wherein said firstinterconnecting structure comprises an electroplated metal.
 45. The chipof claim 39, wherein said first interconnecting structure comprises adamascene metal.
 46. The chip of claim 39, wherein said thirdinterconnecting structure comprises copper.
 47. The chip of claim 39,wherein said third interconnecting structure comprises gold.
 48. Thechip of claim 39 further comprising a third dielectric layer over saidpassivation layer, wherein said third dielectric layer comprises aportion on said top surface of said third interconnecting structure. 49.The chip of claim 48, wherein said third dielectric layer comprises apolymer.
 50. The chip of claim 39 further comprising a third dielectriclayer over said passivation layer, wherein said third dielectric layercomprises a portion between said third interconnecting structure andsaid passivation layer, wherein said third dielectric layer comprises apolymer.